To be honest, most of these issues are due to MultiBit HD basically being abandoned by the devs. The wallet has become more and more unstable. Just look at the number of threads regarding "Password did not unlock the wallet" or "transactions changing to unconfirmed".
The issues have been ongoing for weeks/months and the last commit on github was in March!!?!
Even the MB Devs recommend you use something else:
And for the record, I don't recommend MBHD, either. Move your keys to electrum. No need to pay fees.